Telecommunication providers are increasingly incorporating antennas having remotely adjustable beam characteristics. Such antennas may include adjustable down tilt, beam width, azimuth steering or more complex beam shaping. Where such adjustment is performed electrically (i.e. by altering the electrical characteristics of the feed path) it is desirable to be able to accurately measure the beam characteristics after adjustment.
Where electromechanical actuators are used the physical movement of such actuators may be monitored by sliding or rotating sensors such as potentiometers. Such sensors may require calibration at the time of manufacture, be prone to wear and may not represent the true phase shift produced by a phase shifting network due to non-linearities of the sensor or phase shifting network.
An alternative approach is to sense the phase or amplitude of signals supplied to each radiating element of an array and determine the beam shape based on relative phase or amplitude differences. This approach may require a large number of sensors and require complex calculations to determine the beam pattern. It may therefore be complex and expensive to implement.
It would be desirable to provide an inexpensive, reliable and accurate technique for determining antenna beam attributes utilizing a sensing arrangement and relatively low computational requirements.